1. Field of the Invention
The present invention relates to an inverted blade metering unit for coating a web backed by a rotatable backing roll with a coating mix.
The invention also concerns a method for metering coating mix onto a material web.
2. Description of Related Art
Disclosed in FI patent application 861241 is a method and apparatus for coating a web. The method according to the publication uses a flexible blade for the preapplication of the mix, while the final doctoring is performed by a scraping doctor blade. The coater apparatus is placed to the side of the backing roll allowing the coating mix to meet the web over a great length of the web. Removal of entrained air from the coating mix is awkward in the disclosed method, and the integrated construction of the doctor blade with the coater structure complicates service operations. Further, coating mix behavior in the disclosed method is sensitive to disturbances in the application zone such as uneven distribution of mix quantity. Typical consequences therefrom include striping of web coating in the machine direction of the web.